Holbrook 9401374 Upcoming Delaware multichannel seismic experiment across the Aleutian Arc will collect high quality vertical incidence seismic refraction data across and active continental and island arc system. The PI's will piggyback on this cruise to record sound energy generated by airguns at the ocean bottom. This will provide deep velocity structure data of both continental and oceanic arcs as well as direct imaging of wide-angle reflectivity from the system boundaries. The data will help reconcile conflicting hypothesis of deep structure and composition of the arc systems.